This help page needs to be updated. The reason given is: this manual may contain out of date images. Please help update this help page to reflect recent events or newly available information. Relevant discussion may be found on the talk page. (February 2020) |
Anyone can edit Wikipedia. Most of the time that's a good thing—millions of people have made positive contributions to the largest group-writing effort in human history. Then there are the problem children: those who can't resist the urge to deface an article, or delete all its content (a practice known as blanking a page), and those who add incorrect information, deliberately or by mistake. Fortunately, Wikipedia has robust change-tracking built into it: Whatever one editor does, another can reverse, returning an article to precisely what it was before.
Apart from vandalism, as an editor you're likely to want to see what other editors do to articles you've edited, whether they're on your watchlist (see the section about your watchlist) or not. While Wikipedia's change-tracking system isn't hard to understand, you'll probably find it isn't totally intuitive. In this chapter you'll learn how to quickly read through even a convoluted page history, how to see what's happened since you last edited an article, how to restore an earlier version of an article with just a few clicks, and how to deal with a problem edit followed by other edits you don't want to delete.
When you're working on, say, an Excel spreadsheet, you can't turn back time and look at what the document was like last Tuesday at 10:05 a.m. Wikipedia is different—its database has a copy of every version of every page ever created or edited. If you click on a page history tab, you can see the text on that page at whatever date and time you pick. The page history also shows you every single edit since then (or before then, for that matter).
Keeping a copy of every revision of every page means storing a lot of data. But it's integral to Wikipedia's success. Here are the main benefits to having a record of everything:
If you want to look at individual edits to and prior versions of a page, near the top of the window, just click the "history" tab. The list that appears shows the most recent edits/versions—up to 50, if the page has been edited that many times. The list's top row is the most recent version of the article; the bottom row is the oldest, as you see if you look at the dates and times.
You can use a page history in one of three ways:
This section shows you how to read and interpret a page history in detail.
You can learn a lot by simply reading a page history. Figure 5-1 is a snapshot of the history page for the Wikipedia article on Thomas Kean. If you've never seen a history page before, it probably looks confusing. But each of its many elements has a simple purpose.
Here's a grand tour of the page history for the Thomas Kean article in Figure 5-1:
Moving from politics to movies, consider Figure 5-2, another screenshot of a page history, this time for the article on Clark Gable. Now that you know what all these little words and links represent, you can use them to get a sense of how the page has evolved over time. The page history gives you facts. You have to figure out what it all means.
Reading the page history for the Clark Gable article, you'll notice the following facts and make some related inferences:
In the next section, you'll look at what actually changed with this mysterious edit. If you care enough about an article to take a look at its history, you probably want to take a peek at any such potentially questionable edits you come across.
Once you've got an overview of a page history, you can stop right there, or take it a step further—look at actual edits to see who changed what. If a glance through the page history doesn't make you suspect vandalism (for example, vandalism is unlikely if the last edit was more than a week ago, and by a registered editor with a user page and a user talk page), you can go ahead and edit the article without probing more deeply. But most of the time you're going to be curious about one or more specific (usually recent) edits, for one reason or another. In addition, when you're starting out, looking at others' edits is a good way to learn about how to edit Wikipedia.
Fortunately, you could pretty quickly go ahead and look. When you want to see what one or more editors have changed in an article, you ask the software to compare one version of the page against another version. The resulting output, the difference between versions, is the actual edit.
Any single edit of a page is the difference between one version of a page (one row in the page history) and the version immediately before it (the row below it). You have two ways to get a diff for a single edit. The slow way is to use the two columns of radio buttons, and then click "Compare selected versions" (or press Enter). The fast way is to click the "last" link, on the left side of the version you're interested in.
Time to take a closer look at that anonymous edit in Figure 5-2 to see whether it was vandalism. When you click "last" on the row for the edit of 21:15, 12 February, you get something that looks like Figure 5-3.
Here's how to read the various elements on a diff page:
You now know how to see what changed in a single edit. But often you'll want to see what changed in a group of consecutive edits. For example, suppose you edited an article 2 days ago and want to see everything that's changed. If there were 10 edits since then, you would want to see, in one place, everything that's changed; you don't want to have to do 10 different diffs. Or suppose several different anonymous editors have edited an article recently. By looking only at the net effect of all the recent edits, you don't have to bother dealing with vandalism by one editor, if another editor has already fixed it.
To take Figure 5-2 as an example, suppose you want to see in a single place what editor John Broughton did in his six edits. You can view multiple edits simultaneously in one of two different ways: a quick way that works only in limited circumstances, and a slower way that works anytime. Figure 5-4 shows the tools for both options.
If the 02:56, 13 February 2007 edit was the most recent, you can quickly see what changed in the six edits of interest in Figure 5-4 when you go to the row for the 21:15, 12 February version (the one just before the edits of interest), and click "cur". That click tells the software to compare that version to the current version; the difference between the two versions, of course, is the six edits.
The quick way's limitation, of course, is you can only use it when you're comparing the current version to a prior version—that is, you're looking at a consecutive group of edits up to and including the most recent. The quick approach doesn't work if you want to compare one old version to another old version of the article, to see what changed between them; for example, if an edit (according to its edit summary) fixed vandalism, but you suspect it didn't completely correct the vandalism of the immediately proceeding edit. If you can't use the quick way, the slower (but universal) way to see what happened in a group of consecutive edits is to use the two columns of radio buttons. In the first column, select the "before" version; in the second column, select the "after" version (Figure 5-4). Then press Enter or click "Compare selected versions".
As mentioned earlier in the chapter, you can use a page history in three ways: Read it to get an overview, view and compare edits, or get to any prior version of the page. That third option is the least useful, since you can better figure out what's changed on a page by looking at the actual edits, but you can see what an article used to say at an earlier point in time if you really want to.
To see the text of any specific prior version of a page, simply click its time and date on the history page. Bear in mind that Wikipedia stores the text of a page version in its database, but doesn't keep a record of any images or templates that were on the page at that time. Instead, the software recreates a prior version of a page inserting the current image and templates into it.
In other words, you're not looking at an exact copy of an older version of a page, as it would have looked. But that usually doesn't matter, since it's almost always the text you're concerned about, rather than images or templates. (If you want to see what the image looked like at the time, click the image, which takes you to the history page for that image. Similarly, if you're concerned with the template, click it to go to the history page of the template to see what, if anything, changed before the current version.)
If you're reading an article in Wikipedia and see vandalism, unencylopedic links to commercial or personal Web sites (linkspam), or some other blatant policy violation, your first impulse may be to click "edit this page" and fix the problem. Resist that urge. Manually deleting offending text is error-prone and time-consuming. And, worst of all, if the vandal or spammer deleted or overwrote text while doing the dirty deed, simply removing the problem still leaves the article damaged, since good information is now missing.
Instead, use options in the page history to revert the problematic edit(s). Reverting restores any content that was overwritten or deleted, and removes offending text, putting the article back to what it was before it was vandalized or spammed. Reverting is one of the most powerful features of wiki software. This section shows you how to do a revert in just a few easy steps.
There are two ways to revert an edit. The simplest is to change the damaged page so that the current version of the page was reset to an older, good version. If the last good version was, say, as of Wednesday at 10:00 UTC, then the software would essentially copy that version, overwriting all the changes (edits) made after that time and date.
For the majority of vandalism cases, this kind of revert is sufficient, because good editors check page histories for signs of likely vandalism before editing, and because anti-vandalism activities (which you can read more about in Chapter 7: Dealing with vandalism and spam) identify most vandalism shortly after it appears. But the major drawback of this approach is clear—what if one or more constructive edits came after the problem edit occurred?
The other option—undoing one or more consecutive edits that aren't the most recent—offers a way off the horns of that dilemma. It's usually possible (more details below regarding "usually") to get Wikipedia software to revert interior edits—ones that don't include the most recent edit. Unlike a revert, an undo retains good edits that occurred after the problem edit, creating a truly new version of the article.
Say you're looking at five edits of an article, one per day starting on January 1. The edits on January 4 and 5 were constructive; you want to keep those. The edits on January 2 and 3 were vandalism. The edit on January 1 was constructive, and there's no vandalism prior to that. Using the revert approach, you'd have to revert the article to the last good version (the one on January 1), and then manually add back the good edits of January 4 and 5. That would be the only way to avoid denying the readers of Wikipedia the good information and penalizing the editors who supplied it but missed the vandalism. In this case, you now can use undo to remove only the two vandal edits.
On the other hand, if you want to revert only the most recent edit, or the last few edits (say the edits from January 2 through the 5 were all vandalism), then you can use either revert to a prior version or undo. Both are four-step processes that take roughly the same amount of time. As a bonus, if you're reverting only one edit, the undo option has the advantage of automatically adding information to the edit summary.
So if undo works all the time, while reverting is useful only sometimes, why learn both processes? There's one advantage to using the classic revert: Unlike an undo, with a revert it's impossible to have an edit conflict (see the section about edit conflicts). If you're reverting vandalism on a high-traffic page (today's featured article on the Main Page is a prominent example), an edit conflict could significantly slow your fixing of some highly visible vandalism. So knowing how to revert can still be useful for relatively rare cases.
Doing an undo is a four-step process, starting from the history page. (If you're starting from a diff page (see the section about diffs), then just skip step 1.)
1. Select the edit(s) you want to undo.
2. On the diff page, click "undo" at upper right, above the right column of text (Figure 5-3).
3. If the top of the page reads, "The edit could not be undone due to conflicting intermediate edits", and you're looking at an edit window (don't start editing), then turn to Plan B:
4. Edit or add to the edit summary.
5. Below the editing window, click the "Publish page" button.
Reverting to a prior version is appropriate only if, after looking at one or more edits, you decide that the most recent edit or edits should be reversed; for example, someone has just vandalized a page and the next-to-last version of the page is vandalism-free.
Doing this type of revert is a four-step process, starting from the history page:
1. Click the row for the last good version of the page.
2. At the top of the page, click the "edit this page" tab.
3. At the bottom of the edit window, add an edit summary.
4. Click the "Publish page" button.
After you've undone or reverted an edit (clicked the "Publish page" button), it's a good idea to glance at the page to see if it reads the way you expect. If the undo or revert doesn't seem to have happened, refresh the page in your web browser; pressing Ctrl+R (⌘-R on a Mac) does the trick in most browsers. If the problem is gone, your revert was successful. Congratulate yourself for improving Wikipedia. If you do see some vandalism that you missed, then you can fix it with another undo, if possible, or by doing a direct edit if necessary.
Once you've mastered the steps in the previous section, you can revert or undo any edit on any Wikipedia page. You can lead a long, happy life without going any further. But if you devote yourself to lots of article repair and restoration, you may appreciate help from some power-user tools, like the three described next.
If you're an experienced editor who spends a lot of time looking at page histories, consider some customization to enhance the history display:
.diffchange {padding: 0px 2px 0px 2px; border: 1px dashed red; margin: 0px 1px 0px 0px}
You may find yourself digging through a large number of prior versions of a page, trying to identify exactly who added a given bit of text, and when (for example, to find out if whoever added the text did anything else questionable at the same time). After scrolling through history pages and searching through a large number of versions of the page, you might think: "There has to be a better way." In fact, there is; you have two alternatives:
Sometimes you'll want to know the names of the editors who did the greatest number of edits to an article, or other statistics about edits to a particular page. Wikipedia has a number of tools to count edits, sort edits by contributor, generate statistics about contributors to a page, and so on. Two places to start are:
This help page needs to be updated. The reason given is: this manual may contain out of date images. Please help update this help page to reflect recent events or newly available information. Relevant discussion may be found on the talk page. (February 2020) |
Anyone can edit Wikipedia. Most of the time that's a good thing—millions of people have made positive contributions to the largest group-writing effort in human history. Then there are the problem children: those who can't resist the urge to deface an article, or delete all its content (a practice known as blanking a page), and those who add incorrect information, deliberately or by mistake. Fortunately, Wikipedia has robust change-tracking built into it: Whatever one editor does, another can reverse, returning an article to precisely what it was before.
Apart from vandalism, as an editor you're likely to want to see what other editors do to articles you've edited, whether they're on your watchlist (see the section about your watchlist) or not. While Wikipedia's change-tracking system isn't hard to understand, you'll probably find it isn't totally intuitive. In this chapter you'll learn how to quickly read through even a convoluted page history, how to see what's happened since you last edited an article, how to restore an earlier version of an article with just a few clicks, and how to deal with a problem edit followed by other edits you don't want to delete.
When you're working on, say, an Excel spreadsheet, you can't turn back time and look at what the document was like last Tuesday at 10:05 a.m. Wikipedia is different—its database has a copy of every version of every page ever created or edited. If you click on a page history tab, you can see the text on that page at whatever date and time you pick. The page history also shows you every single edit since then (or before then, for that matter).
Keeping a copy of every revision of every page means storing a lot of data. But it's integral to Wikipedia's success. Here are the main benefits to having a record of everything:
If you want to look at individual edits to and prior versions of a page, near the top of the window, just click the "history" tab. The list that appears shows the most recent edits/versions—up to 50, if the page has been edited that many times. The list's top row is the most recent version of the article; the bottom row is the oldest, as you see if you look at the dates and times.
You can use a page history in one of three ways:
This section shows you how to read and interpret a page history in detail.
You can learn a lot by simply reading a page history. Figure 5-1 is a snapshot of the history page for the Wikipedia article on Thomas Kean. If you've never seen a history page before, it probably looks confusing. But each of its many elements has a simple purpose.
Here's a grand tour of the page history for the Thomas Kean article in Figure 5-1:
Moving from politics to movies, consider Figure 5-2, another screenshot of a page history, this time for the article on Clark Gable. Now that you know what all these little words and links represent, you can use them to get a sense of how the page has evolved over time. The page history gives you facts. You have to figure out what it all means.
Reading the page history for the Clark Gable article, you'll notice the following facts and make some related inferences:
In the next section, you'll look at what actually changed with this mysterious edit. If you care enough about an article to take a look at its history, you probably want to take a peek at any such potentially questionable edits you come across.
Once you've got an overview of a page history, you can stop right there, or take it a step further—look at actual edits to see who changed what. If a glance through the page history doesn't make you suspect vandalism (for example, vandalism is unlikely if the last edit was more than a week ago, and by a registered editor with a user page and a user talk page), you can go ahead and edit the article without probing more deeply. But most of the time you're going to be curious about one or more specific (usually recent) edits, for one reason or another. In addition, when you're starting out, looking at others' edits is a good way to learn about how to edit Wikipedia.
Fortunately, you could pretty quickly go ahead and look. When you want to see what one or more editors have changed in an article, you ask the software to compare one version of the page against another version. The resulting output, the difference between versions, is the actual edit.
Any single edit of a page is the difference between one version of a page (one row in the page history) and the version immediately before it (the row below it). You have two ways to get a diff for a single edit. The slow way is to use the two columns of radio buttons, and then click "Compare selected versions" (or press Enter). The fast way is to click the "last" link, on the left side of the version you're interested in.
Time to take a closer look at that anonymous edit in Figure 5-2 to see whether it was vandalism. When you click "last" on the row for the edit of 21:15, 12 February, you get something that looks like Figure 5-3.
Here's how to read the various elements on a diff page:
You now know how to see what changed in a single edit. But often you'll want to see what changed in a group of consecutive edits. For example, suppose you edited an article 2 days ago and want to see everything that's changed. If there were 10 edits since then, you would want to see, in one place, everything that's changed; you don't want to have to do 10 different diffs. Or suppose several different anonymous editors have edited an article recently. By looking only at the net effect of all the recent edits, you don't have to bother dealing with vandalism by one editor, if another editor has already fixed it.
To take Figure 5-2 as an example, suppose you want to see in a single place what editor John Broughton did in his six edits. You can view multiple edits simultaneously in one of two different ways: a quick way that works only in limited circumstances, and a slower way that works anytime. Figure 5-4 shows the tools for both options.
If the 02:56, 13 February 2007 edit was the most recent, you can quickly see what changed in the six edits of interest in Figure 5-4 when you go to the row for the 21:15, 12 February version (the one just before the edits of interest), and click "cur". That click tells the software to compare that version to the current version; the difference between the two versions, of course, is the six edits.
The quick way's limitation, of course, is you can only use it when you're comparing the current version to a prior version—that is, you're looking at a consecutive group of edits up to and including the most recent. The quick approach doesn't work if you want to compare one old version to another old version of the article, to see what changed between them; for example, if an edit (according to its edit summary) fixed vandalism, but you suspect it didn't completely correct the vandalism of the immediately proceeding edit. If you can't use the quick way, the slower (but universal) way to see what happened in a group of consecutive edits is to use the two columns of radio buttons. In the first column, select the "before" version; in the second column, select the "after" version (Figure 5-4). Then press Enter or click "Compare selected versions".
As mentioned earlier in the chapter, you can use a page history in three ways: Read it to get an overview, view and compare edits, or get to any prior version of the page. That third option is the least useful, since you can better figure out what's changed on a page by looking at the actual edits, but you can see what an article used to say at an earlier point in time if you really want to.
To see the text of any specific prior version of a page, simply click its time and date on the history page. Bear in mind that Wikipedia stores the text of a page version in its database, but doesn't keep a record of any images or templates that were on the page at that time. Instead, the software recreates a prior version of a page inserting the current image and templates into it.
In other words, you're not looking at an exact copy of an older version of a page, as it would have looked. But that usually doesn't matter, since it's almost always the text you're concerned about, rather than images or templates. (If you want to see what the image looked like at the time, click the image, which takes you to the history page for that image. Similarly, if you're concerned with the template, click it to go to the history page of the template to see what, if anything, changed before the current version.)
If you're reading an article in Wikipedia and see vandalism, unencylopedic links to commercial or personal Web sites (linkspam), or some other blatant policy violation, your first impulse may be to click "edit this page" and fix the problem. Resist that urge. Manually deleting offending text is error-prone and time-consuming. And, worst of all, if the vandal or spammer deleted or overwrote text while doing the dirty deed, simply removing the problem still leaves the article damaged, since good information is now missing.
Instead, use options in the page history to revert the problematic edit(s). Reverting restores any content that was overwritten or deleted, and removes offending text, putting the article back to what it was before it was vandalized or spammed. Reverting is one of the most powerful features of wiki software. This section shows you how to do a revert in just a few easy steps.
There are two ways to revert an edit. The simplest is to change the damaged page so that the current version of the page was reset to an older, good version. If the last good version was, say, as of Wednesday at 10:00 UTC, then the software would essentially copy that version, overwriting all the changes (edits) made after that time and date.
For the majority of vandalism cases, this kind of revert is sufficient, because good editors check page histories for signs of likely vandalism before editing, and because anti-vandalism activities (which you can read more about in Chapter 7: Dealing with vandalism and spam) identify most vandalism shortly after it appears. But the major drawback of this approach is clear—what if one or more constructive edits came after the problem edit occurred?
The other option—undoing one or more consecutive edits that aren't the most recent—offers a way off the horns of that dilemma. It's usually possible (more details below regarding "usually") to get Wikipedia software to revert interior edits—ones that don't include the most recent edit. Unlike a revert, an undo retains good edits that occurred after the problem edit, creating a truly new version of the article.
Say you're looking at five edits of an article, one per day starting on January 1. The edits on January 4 and 5 were constructive; you want to keep those. The edits on January 2 and 3 were vandalism. The edit on January 1 was constructive, and there's no vandalism prior to that. Using the revert approach, you'd have to revert the article to the last good version (the one on January 1), and then manually add back the good edits of January 4 and 5. That would be the only way to avoid denying the readers of Wikipedia the good information and penalizing the editors who supplied it but missed the vandalism. In this case, you now can use undo to remove only the two vandal edits.
On the other hand, if you want to revert only the most recent edit, or the last few edits (say the edits from January 2 through the 5 were all vandalism), then you can use either revert to a prior version or undo. Both are four-step processes that take roughly the same amount of time. As a bonus, if you're reverting only one edit, the undo option has the advantage of automatically adding information to the edit summary.
So if undo works all the time, while reverting is useful only sometimes, why learn both processes? There's one advantage to using the classic revert: Unlike an undo, with a revert it's impossible to have an edit conflict (see the section about edit conflicts). If you're reverting vandalism on a high-traffic page (today's featured article on the Main Page is a prominent example), an edit conflict could significantly slow your fixing of some highly visible vandalism. So knowing how to revert can still be useful for relatively rare cases.
Doing an undo is a four-step process, starting from the history page. (If you're starting from a diff page (see the section about diffs), then just skip step 1.)
1. Select the edit(s) you want to undo.
2. On the diff page, click "undo" at upper right, above the right column of text (Figure 5-3).
3. If the top of the page reads, "The edit could not be undone due to conflicting intermediate edits", and you're looking at an edit window (don't start editing), then turn to Plan B:
4. Edit or add to the edit summary.
5. Below the editing window, click the "Publish page" button.
Reverting to a prior version is appropriate only if, after looking at one or more edits, you decide that the most recent edit or edits should be reversed; for example, someone has just vandalized a page and the next-to-last version of the page is vandalism-free.
Doing this type of revert is a four-step process, starting from the history page:
1. Click the row for the last good version of the page.
2. At the top of the page, click the "edit this page" tab.
3. At the bottom of the edit window, add an edit summary.
4. Click the "Publish page" button.
After you've undone or reverted an edit (clicked the "Publish page" button), it's a good idea to glance at the page to see if it reads the way you expect. If the undo or revert doesn't seem to have happened, refresh the page in your web browser; pressing Ctrl+R (⌘-R on a Mac) does the trick in most browsers. If the problem is gone, your revert was successful. Congratulate yourself for improving Wikipedia. If you do see some vandalism that you missed, then you can fix it with another undo, if possible, or by doing a direct edit if necessary.
Once you've mastered the steps in the previous section, you can revert or undo any edit on any Wikipedia page. You can lead a long, happy life without going any further. But if you devote yourself to lots of article repair and restoration, you may appreciate help from some power-user tools, like the three described next.
If you're an experienced editor who spends a lot of time looking at page histories, consider some customization to enhance the history display:
.diffchange {padding: 0px 2px 0px 2px; border: 1px dashed red; margin: 0px 1px 0px 0px}
You may find yourself digging through a large number of prior versions of a page, trying to identify exactly who added a given bit of text, and when (for example, to find out if whoever added the text did anything else questionable at the same time). After scrolling through history pages and searching through a large number of versions of the page, you might think: "There has to be a better way." In fact, there is; you have two alternatives:
Sometimes you'll want to know the names of the editors who did the greatest number of edits to an article, or other statistics about edits to a particular page. Wikipedia has a number of tools to count edits, sort edits by contributor, generate statistics about contributors to a page, and so on. Two places to start are: